Issue #21644 has been reported by viralpraxis (Iaroslav Kurbatov). ---------------------------------------- Bug #21644: Stack consistency error for the `newrange` INSN peephole optimization with chilled string https://bugs.ruby-lang.org/issues/21644 * Author: viralpraxis (Iaroslav Kurbatov) * Status: Open * ruby -v: ruby 3.4.7 (2025-10-08 revision 7a5688e2a2) +PRISM [x86_64-linux] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- PR:https://github.com/ruby/ruby/pull/14879 Confirmed on every version since 3.4. ``` shell $ ruby -v -e '("a" || "b").."c"' ruby 3.4.7 (2025-10-08 revision 7a5688e2a2) +PRISM [x86_64-linux] -e:1: warning: possibly useless use of .. in void context -e:1: [BUG] Stack consistency error (sp: 7, bp: 6) ruby 3.4.7 (2025-10-08 revision 7a5688e2a2) +PRISM [x86_64-linux] -- Control frame information ----------------------------------------------- c:0002 p:0013 s:0007 e:000005 EVAL -e:1 [FINISH] c:0001 p:0000 s:0003 E:001920 DUMMY [FINISH] -- Ruby level backtrace information ---------------------------------------- -e:1:in '<main>' -- Threading information --------------------------------------------------- Total ractor count: 1 Ruby thread count for this ractor: 1 -- C level backtrace information ------------------------------------------- ruby/3.4.7/lib/libruby.so.3.4(rb_print_backtrace+0x8) [0x78aa9573c882] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_dump.c:823 ruby/3.4.7/lib/libruby.so.3.4(rb_vm_bugreport) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_dump.c:1155 ruby/3.4.7/lib/libruby.so.3.4(rb_bug_without_die_internal+0x6b) [0x78aa9544c62f] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/error.c:1097 ruby/3.4.7/lib/libruby.so.3.4(rb_bug) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/error.c:1115 ruby/3.4.7/lib/libruby.so.3.4(vm_stack_consistency_error+0x1f) [0x78aa9544f091] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_insnhelper.c:6523 ruby/3.4.7/lib/libruby.so.3.4(vm_get_cref) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/insns.def:1134 ruby/3.4.7/lib/libruby.so.3.4(vm_setclassvariable) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_insnhelper.c:1630 ruby/3.4.7/lib/libruby.so.3.4(vm_setclassvariable) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_insnhelper.c:1627 ruby/3.4.7/lib/libruby.so.3.4(vm_exec_core) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/insns.def:253 ruby/3.4.7/lib/libruby.so.3.4(vm_exec_loop+0xa) [0x78aa95724959] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm.c:2622 ruby/3.4.7/lib/libruby.so.3.4(rb_vm_exec) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm.c:2598 ruby/3.4.7/lib/libruby.so.3.4(rb_ec_exec_node+0xa5) [0x78aa95525695] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/eval.c:281 ruby/3.4.7/lib/libruby.so.3.4(ruby_run_node+0x83) [0x78aa95529333] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/eval.c:319 ruby/3.4.7/bin/ruby(rb_main+0x21) [0x59d86f5e0186] ./main.c:43 ruby/3.4.7/bin/ruby(main) ./main.c:68 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_call_main+0x7a) [0x78aa9502a1ca] ../sysdeps/nptl/libc_start_call_main.h:58 /lib/x86_64-linux-gnu/libc.so.6(call_init+0x0) [0x78aa9502a28b] ../csu/libc-start.c:360 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main_impl) ../csu/libc-start.c:347 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main) (null):0 [0x59d86f5e01d5] ``` The optimization in question: https://github.com/ruby/ruby/blob/957c832db137e67289e93dfd9fd9e915b1f2fc87/c... Before entering this `newrange` optimization, the iseq looks like this: ``` == disasm: #<ISeq:<compiled>@<compiled>:1 (1,0)-(1,17)> 0000 putchilledstring "a" ( 1)[Li] 0002 dup 0003 branchif 8 0005 pop 0006 putchilledstring "b" 0008 putchilledstring "c" 0010 newrange 0 0012 leave ``` So the optimization constructs a new range using the wrong operands (`"b"` and `"c"` instead of `"a"` and `"c"`). Also, I'm wondering why chilled strings are not ||-peephole-optimized? ``` ruby ruby --dump insn -ve '"a" || "b"' ruby 3.5.0dev (2025-10-19T14:22:25Z master 957c832db1) +PRISM [x86_64-linux] == disasm: #<ISeq:<main>@-e:1 (1,0)-(1,10)> 0000 putchilledstring "a" ( 1)[Li] 0002 dup 0003 branchif 8 0005 pop 0006 putchilledstring "b" 0008 leave ``` ```ruby ruby --enable-frozen-string-literal --dump insn -ve '"a" || "b"' ruby 3.5.0dev (2025-10-19T14:22:25Z master 957c832db1) +PRISM [x86_64-linux] == disasm: #<ISeq:<main>@-e:1 (1,0)-(1,10)> 0000 putobject "a" ( 1)[Li] 0002 leave ``` ```ruby ruby --disable-frozen-string-literal --dump insn -ve '"a" || "b"' ruby 3.5.0dev (2025-10-19T14:22:25Z master 957c832db1) +PRISM [x86_64-linux] == disasm: #<ISeq:<main>@-e:1 (1,0)-(1,10)> 0000 putstring "a" ( 1)[Li] 0002 leave ``` -- https://bugs.ruby-lang.org/